[llvm] r369841 - [InstCombine] matchThreeWayIntCompare(): commutativity awareness
Roman Lebedev via llvm-commits
llvm-commits at lists.llvm.org
Fri Aug 23 23:49:36 PDT 2019
Author: lebedevri
Date: Fri Aug 23 23:49:36 2019
New Revision: 369841
URL: http://llvm.org/viewvc/llvm-project?rev=369841&view=rev
Log:
[InstCombine] matchThreeWayIntCompare(): commutativity awareness
Summary:
`matchThreeWayIntCompare()` looks for
```
select i1 (a == b),
i32 Equal,
i32 (select i1 (a < b), i32 Less, i32 Greater)
```
but both of these selects/compares can be in it's commuted form,
so out of 8 variants, only the two most basic ones is handled.
This fixes regression being introduced in D66232.
Reviewers: spatel, nikic, efriedma, xbolva00
Reviewed By: spatel
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66607
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
llvm/trunk/test/Transforms/InstCombine/unrecognized_three-way-comparison.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=369841&r1=369840&r2=369841&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Fri Aug 23 23:49:36 2019
@@ -2562,20 +2562,49 @@ bool InstCombiner::matchThreeWayIntCompa
// TODO: Generalize this to work with other comparison idioms or ensure
// they get canonicalized into this form.
- // select i1 (a == b), i32 Equal, i32 (select i1 (a < b), i32 Less, i32
- // Greater), where Equal, Less and Greater are placeholders for any three
- // constants.
- ICmpInst::Predicate PredA, PredB;
- if (match(SI->getTrueValue(), m_ConstantInt(Equal)) &&
- match(SI->getCondition(), m_ICmp(PredA, m_Value(LHS), m_Value(RHS))) &&
- PredA == ICmpInst::ICMP_EQ &&
- match(SI->getFalseValue(),
- m_Select(m_ICmp(PredB, m_Specific(LHS), m_Specific(RHS)),
- m_ConstantInt(Less), m_ConstantInt(Greater))) &&
- PredB == ICmpInst::ICMP_SLT) {
- return true;
+ // select i1 (a == b),
+ // i32 Equal,
+ // i32 (select i1 (a < b), i32 Less, i32 Greater)
+ // where Equal, Less and Greater are placeholders for any three constants.
+ ICmpInst::Predicate PredA;
+ if (!match(SI->getCondition(), m_ICmp(PredA, m_Value(LHS), m_Value(RHS))) ||
+ !ICmpInst::isEquality(PredA))
+ return false;
+ Value *EqualVal = SI->getTrueValue();
+ Value *UnequalVal = SI->getFalseValue();
+ // We still can get non-canonical predicate here, so canonicalize.
+ if (PredA == ICmpInst::ICMP_NE)
+ std::swap(EqualVal, UnequalVal);
+ if (!match(EqualVal, m_ConstantInt(Equal)))
+ return false;
+ ICmpInst::Predicate PredB;
+ Value *LHS2, *RHS2;
+ if (!match(UnequalVal, m_Select(m_ICmp(PredB, m_Value(LHS2), m_Value(RHS2)),
+ m_ConstantInt(Less), m_ConstantInt(Greater))))
+ return false;
+ // We can get predicate mismatch here, so canonicalize if possible:
+ // First, ensure that 'LHS' match.
+ if (LHS2 != LHS) {
+ // x sgt y <--> y slt x
+ std::swap(LHS2, RHS2);
+ PredB = ICmpInst::getSwappedPredicate(PredB);
}
- return false;
+ if (LHS2 != LHS)
+ return false;
+ // We also need to canonicalize 'RHS'.
+ if (PredB == ICmpInst::ICMP_SGT && isa<Constant>(RHS2)) {
+ // x sgt C-1 <--> x sge C <--> not(x slt C)
+ auto FlippedStrictness =
+ getFlippedStrictnessPredicateAndConstant(PredB, cast<Constant>(RHS2));
+ if (!FlippedStrictness)
+ return false;
+ assert(FlippedStrictness->first == ICmpInst::ICMP_SGE && "Sanity check");
+ RHS2 = FlippedStrictness->second;
+ // And kind-of perform the result swap.
+ std::swap(Less, Greater);
+ PredB = ICmpInst::ICMP_SLT;
+ }
+ return PredB == ICmpInst::ICMP_SLT && RHS == RHS2;
}
Instruction *InstCombiner::foldICmpSelectConstant(ICmpInst &Cmp,
Modified: llvm/trunk/test/Transforms/InstCombine/unrecognized_three-way-comparison.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/unrecognized_three-way-comparison.ll?rev=369841&r1=369840&r2=369841&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/unrecognized_three-way-comparison.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/unrecognized_three-way-comparison.ll Fri Aug 23 23:49:36 2019
@@ -36,14 +36,10 @@ exit:
define i32 @compare_against_zero(i32 %x) {
; CHECK-LABEL: @compare_against_zero(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i32 [[X:%.*]], 0
-; CHECK-NEXT: [[CMP2_INV:%.*]] = icmp sgt i32 [[X]], -1
-; CHECK-NEXT: [[SELECT1:%.*]] = select i1 [[CMP2_INV]], i32 1, i32 -1
-; CHECK-NEXT: [[SELECT2:%.*]] = select i1 [[CMP1]], i32 0, i32 [[SELECT1]]
-; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SELECT2]], 0
-; CHECK-NEXT: br i1 [[COND]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = icmp sgt i32 [[X:%.*]], 0
+; CHECK-NEXT: br i1 [[TMP0]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
; CHECK: callfoo:
-; CHECK-NEXT: call void @foo(i32 [[SELECT2]])
+; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret i32 42
@@ -96,14 +92,10 @@ exit:
define i32 @compare_against_two(i32 %x) {
; CHECK-LABEL: @compare_against_two(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i32 [[X:%.*]], 2
-; CHECK-NEXT: [[CMP2_INV:%.*]] = icmp sgt i32 [[X]], 1
-; CHECK-NEXT: [[SELECT1:%.*]] = select i1 [[CMP2_INV]], i32 1, i32 -1
-; CHECK-NEXT: [[SELECT2:%.*]] = select i1 [[CMP1]], i32 0, i32 [[SELECT1]]
-; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SELECT2]], 0
-; CHECK-NEXT: br i1 [[COND]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = icmp sgt i32 [[X:%.*]], 2
+; CHECK-NEXT: br i1 [[TMP0]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
; CHECK: callfoo:
-; CHECK-NEXT: call void @foo(i32 [[SELECT2]])
+; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret i32 42
@@ -497,13 +489,10 @@ define i32 @compare_against_fortytwo_com
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP1:%.*]] = icmp ne i32 [[X:%.*]], 42
; CHECK-NEXT: call void @use1(i1 [[CMP1]])
-; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 [[X]], 42
-; CHECK-NEXT: [[SELECT1:%.*]] = select i1 [[CMP2]], i32 -1, i32 1
-; CHECK-NEXT: [[SELECT2:%.*]] = select i1 [[CMP1]], i32 [[SELECT1]], i32 0
-; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SELECT2]], 0
-; CHECK-NEXT: br i1 [[COND]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = icmp sgt i32 [[X]], 42
+; CHECK-NEXT: br i1 [[TMP0]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
; CHECK: callfoo:
-; CHECK-NEXT: call void @foo(i32 [[SELECT2]])
+; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret i32 84
@@ -527,14 +516,10 @@ exit:
define i32 @compare_against_fortytwo_commutatibility_2(i32 %x) {
; CHECK-LABEL: @compare_against_fortytwo_commutatibility_2(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i32 [[X:%.*]], 42
-; CHECK-NEXT: [[CMP2:%.*]] = icmp sgt i32 [[X]], 41
-; CHECK-NEXT: [[SELECT1:%.*]] = select i1 [[CMP2]], i32 1, i32 -1
-; CHECK-NEXT: [[SELECT2:%.*]] = select i1 [[CMP1]], i32 0, i32 [[SELECT1]]
-; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SELECT2]], 0
-; CHECK-NEXT: br i1 [[COND]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = icmp sgt i32 [[X:%.*]], 42
+; CHECK-NEXT: br i1 [[TMP0]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
; CHECK: callfoo:
-; CHECK-NEXT: call void @foo(i32 [[SELECT2]])
+; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret i32 84
@@ -559,13 +544,10 @@ define i32 @compare_against_fortytwo_com
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP1:%.*]] = icmp ne i32 [[X:%.*]], 42
; CHECK-NEXT: call void @use1(i1 [[CMP1]])
-; CHECK-NEXT: [[CMP2:%.*]] = icmp sgt i32 [[X]], 41
-; CHECK-NEXT: [[SELECT1:%.*]] = select i1 [[CMP2]], i32 1, i32 -1
-; CHECK-NEXT: [[SELECT2:%.*]] = select i1 [[CMP1]], i32 [[SELECT1]], i32 0
-; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SELECT2]], 0
-; CHECK-NEXT: br i1 [[COND]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = icmp sgt i32 [[X]], 42
+; CHECK-NEXT: br i1 [[TMP0]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
; CHECK: callfoo:
-; CHECK-NEXT: call void @foo(i32 [[SELECT2]])
+; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret i32 84
@@ -616,14 +598,10 @@ exit:
define i32 @compare_against_arbitrary_value_commutativity1(i32 %x, i32 %c) {
; CHECK-LABEL: @compare_against_arbitrary_value_commutativity1(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i32 [[X:%.*]], [[C:%.*]]
-; CHECK-NEXT: [[CMP2:%.*]] = icmp sgt i32 [[C]], [[X]]
-; CHECK-NEXT: [[SELECT1:%.*]] = select i1 [[CMP2]], i32 -1, i32 1
-; CHECK-NEXT: [[SELECT2:%.*]] = select i1 [[CMP1]], i32 0, i32 [[SELECT1]]
-; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SELECT2]], 0
-; CHECK-NEXT: br i1 [[COND]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = icmp sgt i32 [[X:%.*]], [[C:%.*]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
; CHECK: callfoo:
-; CHECK-NEXT: call void @foo(i32 [[SELECT2]])
+; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret i32 42
@@ -648,13 +626,10 @@ define i32 @compare_against_arbitrary_va
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP1:%.*]] = icmp ne i32 [[X:%.*]], [[C:%.*]]
; CHECK-NEXT: call void @use1(i1 [[CMP1]])
-; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 [[X]], [[C]]
-; CHECK-NEXT: [[SELECT1:%.*]] = select i1 [[CMP2]], i32 -1, i32 1
-; CHECK-NEXT: [[SELECT2:%.*]] = select i1 [[CMP1]], i32 [[SELECT1]], i32 0
-; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SELECT2]], 0
-; CHECK-NEXT: br i1 [[COND]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = icmp sgt i32 [[X]], [[C]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
; CHECK: callfoo:
-; CHECK-NEXT: call void @foo(i32 [[SELECT2]])
+; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret i32 42
@@ -680,13 +655,10 @@ define i32 @compare_against_arbitrary_va
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP1:%.*]] = icmp ne i32 [[X:%.*]], [[C:%.*]]
; CHECK-NEXT: call void @use1(i1 [[CMP1]])
-; CHECK-NEXT: [[CMP2:%.*]] = icmp sgt i32 [[C]], [[X]]
-; CHECK-NEXT: [[SELECT1:%.*]] = select i1 [[CMP2]], i32 -1, i32 1
-; CHECK-NEXT: [[SELECT2:%.*]] = select i1 [[CMP1]], i32 [[SELECT1]], i32 0
-; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SELECT2]], 0
-; CHECK-NEXT: br i1 [[COND]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = icmp sgt i32 [[X]], [[C]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[CALLFOO:%.*]], label [[EXIT:%.*]]
; CHECK: callfoo:
-; CHECK-NEXT: call void @foo(i32 [[SELECT2]])
+; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret i32 42
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